Sneaky Things That Mess Up Your Skin

Congrats! you slathered on sunscreen all summer. But if you're about to pack away the SPF along with your flip-flops…don't. Fall's rays are just as likely as summer's to cause brown spots, wrinkles and skin cancer, warns David Bank, M.D., a dermatologist in Mount Kisco, New York. "Foundation with SPF isn't enough, especially since women typically spread on a superthin layer." Your best strategy: Every morning apply moisturizer with SPF 15 or above. Two good ones: Elizabeth Arden Prevage Day Anti-aging Moisturizer PA++, with SPF 30 and other wrinkle fighters ($125, elizabetharden.com), and Cetaphil UVA/UVB Defense SPF 50 ($14, at drugstores). Now the word on eight more things that could be standing between you and amazing skin:

Skin Spoiler 1: Going to Bed With Your Makeup On

"A surprising number of my patients fall asleep without washing their faces," says Jeffrey Dover, M.D., a Boston dermatologist and coauthor of The Youth Equation. "A lot of them are working late these days. They just collapse into bed." Skipping it once or twice a week is not a problem, but doing it night after night (you know who you are!) can lead to clogged pores and breakouts.

Your skin saver: For those times when you're too zonked to wash, keep a stash of cleansing wipes on your nightstand so you can swipe and crash. (Try Revlon Makeup Remover Towelettes, $6.50, at drugstores.) Otherwise, lather up nightly with a dime-sized drop of cleanser and rinse it off with several good splashes, says David J. Leffell, M.D., professor of dermatology and surgery at the Yale School of Medicine. If you don't completely remove cleanser, it can clog pores. Residue may also prevent the active ingredients in creams from sinking in and doing their job.

Skin Spoiler 2: Getting Squeaky Clean

Dermatologists say they're treating more and more women who use too many types of exfoliators—grainy scrubs, peels and home microdermabrasion kits—and reach for them too often. Scouring yourself like a crud-caked pot causes irritation and (surprise!) slickness; when you strip out natural oils, your skin produces extra to compensate. Exfoliating more than necessary can cause extended harm: "There's a vicious cycle of water loss and cell deterioration," says Dr. Dover. You end up with red, flaky skin that's extra prone to sun damage and wrinkles.

Your skin saver: If yours is normal, exfoliate just once a week. Oily or breakout-prone? Do it twice a week. And if you're on the dry side or extra sensitive, two times a month is plenty. No matter what, if a product burns or tingles, rinse it off. New ways to slough and glow: Bioré Even Smoother Microderm Exfoliator ($15, at drugstores) and Avon Anew Clinical Advanced Retexturizing Peel ($25, avon.com).

Skin Spoiler 3: Eating the Wrong Foods (or Eating Too Little)

If you're starving yourself to fit into a new dress or regularly snacking on processed foods like chips and cookies instead of fruits and veggies, you're losing out on vitamins and nutrients. "You don't have to be perfect all the time," says nutritionist Lauren Slayton, founder of New York City's Foodtrainers, "but for smooth, clear skin you need a well-rounded diet."

Your skin saver: "Women are most lax about getting enough biotin and omega-3 in their diet, both of which are critical for healthy skin," says Slayton. Find them in whole grains, dairy foods, fish and nuts. Also, get in lots of antioxidant-rich produce, including berries and spinach—they help your skin fight off damage. Bonus: Fill yourself up with the good stuff and you'll have less room for all that fatty/salty/sugary crap, no matter how much you crave it.

Skin Spoiler 4: Smoking Cigarettes

About 20 percent of women 18 to 24 smoke, and it may be written all over their faces. "The second I meet a patient, I can tell whether she's a smoker," says Kenneth Beer, M.D., a dermatologist in West Palm Beach, Florida. "She'll have pronounced lines around her mouth and look much older than she is. I worked with one smoker who was 25 but looked 35. Today at 35, she looks 50. She'll look closer to her age only if she stops." Why? Smoking decreases the flow of oxygen and increases the production of rogue molecules know as free radicals, both of which bring on sallowness and wrinkles—a.k.a. "smoker's skin."

Your skin saver: Quit, woman! Getting happier in your own skin may help. In a study conducted by Temple University, in Philadelphia, a group of smokers who received counseling for self-esteem and body image issues were better able to stop than those smokers who had exercise sessions with a trainer; they also lost double the weight. Proven ways to feel better about your body: Work out, eat healthier and talk through I'm-so-fat feelings with encouraging, compliment-giving friends. Over-the-counter nicotine gum can help you end the habit, as can hotlines like 877-44U-QUIT and support sites such as becomeanex.org.

Skin Spoiler 5: Skimping on Sleep

"Between economy anxiety and increased workloads, my patients seem to be sleeping less," says New York City dermatologist Dennis Gross, M.D., echoing what skin doctors around the country told Glamour. Beauty sleep is no myth: "Our body sees a chronic lack of sleep as a state of emergency, which causes it to produce stress hormones," says Dr. Gross. "They signal the body to divert oxygen and nutrients away from skin to major internal organs. When skin doesn't get that optimum fuel, it can break out and become dull, with dark under-eye circles and puffiness."

Your skin saver: There's no getting around it—aim for seven hours of shut-eye. For the days when that's not humanly possible, at least switch off your computer, BlackBerry and Wii an hour before bedtime. A study in the Journal of Applied Physiology suggests that performing tasks in front of a bright display suppresses the production of melatonin, a hormone that helps regulate the sleep-wake cycle; you may spend hours tossing and turning before drifting off, or wake repeatedly throughout the night. For a morning boost, try Garnier Nutritioniste Skin Renew Awakening Face Massager ($13, at drugstores); this editor fave has a roller-ball applicator that glides on a skin-brightening serum.

Skin Spoiler 6: Gaining and Losing the Same 10 Pounds Over and Over

Weight gain and loss, especially when they're done quickly and repeatedly (hello, crash diets and lemon-water cleanses), weaken the fibers of skin, making it prone to premature sagging, stretch marks and little lines. Even putting on and shedding as few as five pounds in rapid succession can upset the body's hormone levels and trigger breakouts.

Your skin saver: If you've yo-yo dieted and your skin's got sag, a lotion like Origins Youthtopia Skin Firming Lotion with Rhodiola ($49, origins.com) may help a little. Most important: Set a goal of losing no more than two pounds per week, a safe, skin-friendly amount. "Slow and steady wins the race," says Jeffrey Morrison, M.D., a New York City doctor who specializes in weight loss and nutrition. Don't go it alone: Consider joining a group that offers support, like WeightWatchers or 3fatchicks.com.

Skin Spoiler 7: Mistaking Rosacea for Acne

It's easy to confuse rosacea's angry red patches, visible blood vessels and inflamed pimples with plain old acne. So easy that 78 percent of the 14 million Americans with the condition don't have the slightest clue they've got it, according to the National Rosacea Society. More women are being diagnosed with it than ever before. Experts chalk up the rise to the wider availability of active ingredients in skin-care products, which may trigger flare-ups, and higher stress levels, which can lower skin's resistance to inflammation and acne.

Your skin saver: If you have any of the above symptoms—or if you have splotches that worsen after workouts, when you eat spicy food or drink alcohol, or when you're under stress—see a dermatologist. She'll probably prescribe Finacea gel, the most common treatment. Doctors also recommend steering clear of products with benzoyl peroxide, glycolic acid and retinol and using ones made to soothe rosacea and tone down redness; try Murad Redness Therapy Correcting Moisturizer SPF 15 ($37, murad.com).

Skin Spoiler 8: Not Having Enough Fun

If you haven't been spending a lot of time with friends lately, a proven stress buster, consider this: "Studies show that stress weakens the barrier that protects skin from elements like pollution and the sun," Dr. Bank says. That puts you more at risk for breakouts, wrinkles, you name it.

Your skin saver: Spread the fun around; don't stockpile it for weekends. "I schedule one night a week with friends in Outlook like I would do for a work appointment," says New York City dermatologist Amy Wechsler, M.D. "This way it's not optional." Another welcome prescription: sex! "During sex you release beta endorphins, which have acne-healing properties," adds Dr. Wechsler. The big O also increases estrogen, which gives skin glow—a nice perk.